AS AN ART DEALER Ramon Osuna, director and owner of Osuna Galleries Inc., likes to bring together artists and collectors. Rather than use his gallery as a gathering place, he prefers to entertain in his 1890s town house on 16th Street NW -- something he does at least three times a week. Filled with Old World masterpieces, the four-story home is a natural setting for lovers of art.

"Ramon's social events are his kind of art," says Carol Goldberg, an artist whose works are shown at Osuna Galleries on Seventh Street. "He has an excellent eye for art, for pulling people together. You don't even need food at his place. You learn so much from his guests."

"A mixture of artists, museum people and collectors usually provides a very good formula for entertaining," Osuna says. "If you get all artists and museum people together, the result is dull. You need a mixture, even of different ages."

For Osuna, a good party begins with the guest list, and preparing it, he feels, is his most difficult task. Once the guests are in his home, he makes sure they mix well with each other -- his second most difficult task.

Osuna never serves any wine except champagne. "That way I don't have to worry about white, red or dessert wine," he explains.

The cocktail period takes place either on the ground floor overlooking the small garden or on the third floor next to the dining room. The cocktail hour is long so that people can really talk to each other. There are usually no hors d'oeuvres, he says, "be- cause I fill myself up on them and then I don't enjoy dinner."

Depending on the size of the dinner party -- his favorite is six or eight for dinner at his Geoffrey Bigelow table -- the guests move from one floor to another. He may have small round tables for a dinner of 30 in his downstairs room, making the guests feel quite the actors with a powerful audience of 17th-century masterpieces. Two round tables may be pushed together for eight people and the silver slightly mismatched, but that only adds to the artistic flavor of the evening.

After gallery openings, Osuna often will have his guests sip their champagne on the first floor and move upstairs for the dinner. "Movement at a dinner party is essential," he says. "That way, people don't get bored sitting in one place."

After dinner, Osuna will have his guests move to a third room for coffee and more champagne.

Osuna selects his own menus and occasionally cooks part of the meal. A native of Cuba, he usually includes one Cuban dish on the menu and asks local Cuban cooks to prepare it for him. Often he'll bring freshly baked guava pastries from Miami and serve them with a hot guava sauce that he makes. A chocoholic, Osuna serves Suzanne's chocolate espresso cheesecake, which he leaves out until it almost melts.

Of all the recipes, the show-stopper is always a Cuban chicken pie covered with a light puffy crust and filled with vegetables, fruits and nuts. Although the woman who makes it for Osuna would not part with her recipe, a Cuban friend provided a version of this great Cuban regional dish. Serve it with a green salad. Maria Luisa Clarens' Pastelon de Pollo Camaguiyano (Cuban Chicken Pie a la Camaguey) Serves eight

1/4 pound butter or margarine

Chicken pie filling:

4 boned whole chicken breasts (marinated with lemon, salt and pepper)

1 tablespoon flour

4 large yellow onions, diced

1/4 cup chopped parsley

1/2 cup golden raisins

1/2 cup slivered almonds

1 pound white mushrooms, cleaned, sliced and lightly saute'ed in butter

1 cup dry white wine or sherry

Prepare the filling the day before:

Melt the butter and brown the chicken in it. Remove the chicken and add the flour to the pan. Add the chicken together with the onions, mushrooms, wine, raisins, almonds and parsley. Lower the heat and cover. Cook until the chicken is tender. Remove the chicken and cut into small pieces. Return the chicken pieces to the sauce. Note: It's important to keep all the liquid from the sauce to use in the pie filling. Without it the pie will be too dry. Pie Pastry

4 cups flour

4 tablespoons granulated sugar

1 teaspoon salt

2 teaspoons baking powder

3/4 cup Crisco or vegetable shortening

1/4 cup unsalted butter

4 eggs, well beaten

2 to 3 tablespoons dry wine

Sift the flour together with the sugar, salt and baking powder. Add the butter and vegetable shortening. Rub the dry ingredients and the fat together rapidly between the tips of your fingers until the fat is broken and has the consistency of coarse meal. Add three of the eggs and the wine and blend quickly to gather dough into a mass. Knead into a smooth round ball. Wrap in waxed paper and place in the freezer for about half an hour. Grease a nine-inch, round pie pan.

Preheat the oven to 425 degrees. Separate the dough into two equal portions. Roll out one of the portions with a roller until it is approximately 1/4-inch thick. Press it in the pie dish and bake in the oven for five minutes. Pour in the chicken filling. Roll out the second portion of the dough to cover the pie. Seal the edges and brush the top with the remaining egg. Make a few cuts with a knife in the top of the pastry. Reduce oven to 350 degrees and bake for around 30 to 40 minutes, until golden.